| // SPDX-License-Identifier: GPL-2.0-or-later |
| |
| #include <linux/export.h> |
| #include <linux/fb.h> |
| #include <linux/mutex.h> |
| |
| #if IS_ENABLED(CONFIG_FB_BACKLIGHT) |
| /* |
| * This function generates a linear backlight curve |
| * |
| * 0: off |
| * 1-7: min |
| * 8-127: linear from min to max |
| */ |
| void fb_bl_default_curve(struct fb_info *fb_info, u8 off, u8 min, u8 max) |
| { |
| unsigned int i, flat, count, range = (max - min); |
| |
| mutex_lock(&fb_info->bl_curve_mutex); |
| |
| fb_info->bl_curve[0] = off; |
| |
| for (flat = 1; flat < (FB_BACKLIGHT_LEVELS / 16); ++flat) |
| fb_info->bl_curve[flat] = min; |
| |
| count = FB_BACKLIGHT_LEVELS * 15 / 16; |
| for (i = 0; i < count; ++i) |
| fb_info->bl_curve[flat + i] = min + (range * (i + 1) / count); |
| |
| mutex_unlock(&fb_info->bl_curve_mutex); |
| } |
| EXPORT_SYMBOL_GPL(fb_bl_default_curve); |
| #endif |
